Home > Publications database > Das Gefüge von Pyrokohlenstoff-Hüllschichten nach der Abscheidung im Fließbett und seine Änderungen durch Bestrahlung |
Book/Report | FZJ-2016-03813 |
; ; ;
1979
Kernforschungsanlage Jülich, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/11836
Report No.: Juel-1609
Abstract: The introducing review of literature is followed by a discussion of some equations to explain image contrast of TEM micrographs of pyrocarbon (PyC). Subsequently methods are described, which allow quantitative measurements of defined properties of the texture of PyC-coatings. The results show that PyC consists of three types of microstructure called components differing by density and/or crystallite size. The gross properties of the coatings such as density or porosity are due to the relative volume-fraction and the arrangement of the components within the coatings. Deposition of the components may be assigned to certain regions of the fluidized bed. This allows to explain how some properties of the coatings depend on deposition conditions. Partially the results are consistent with attempts to describe the deposition process theoretically. After fast neutron irradiation microcracks are found within each of the three components. The quantity of microcracks per unit area of any plane through the PyC-coating is described by a specific crack-length. The specific crack-length increases with fast neutron fluence and is due to the as-deposited properties of the coatings. The results suggest that gaseous fission products are released by these microcracks.
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